Not Applicable
Not applicable
Not Applicable
1. Field of the Invention
The present invention relates to the detection of security features on monetary documents and the like. The US Federal Government has taken steps in recent years to combat counterfeiting of paper currency. Other monetary issuing agencies throughout the world have taken like steps. Additionally, banking organizations have added security features to other documents such as checks to impede forgery.
2. The Prior Art
The advent of inexpensive computer and color printing and copying systems has made counterfeiting a much easier task than heretofore possible. As such, the US Government and other monetary issuing agencies have added a number of very difficult to duplicate features to the paper currency. The list below is particular to the US $10 bill but is indicative of the remainder of commonly circulated United States currencies.
1. Federal Reserve Indicatorsxe2x80x94A new universal seal represents the entire Federal Reserve System. A letter and number beneath the left serial number identify the issuing Federal Reserve Bank.
2. Portraitxe2x80x94The enlarged portrait of the first Secretary of the Treasury, Alexander Hamilton is easier to recognize, while the added detail is harder to duplicate. The portrait is now off-center, providing room for a watermark and reducing wear and tear on the portrait.
3. Security Threadxe2x80x94A polymer thread embedded vertically in the paper to the right of the portrait indicates the $10 denomination. The words xe2x80x9cUSA TENxe2x80x9d and a flag can be seen from both sides of the notes when held up to a bright light. The number xe2x80x9c10xe2x80x9d appears in the star field of the flag. Additionally, this thread glows orange when held under an ultraviolet light.
4. Watermarkxe2x80x94A watermark based on the same artwork as the portrait is visible from both sides when held up to a light.
5. Color-Shifting Inkxe2x80x94The number in the lower right corner on the front of the note looks green when viewed straight on, but appears black when viewed at an angle.
6. Serial Numbersxe2x80x94An additional letter is added to the serial number. The unique combination of eleven numbers and letters appears twice on the front of the note.
7. Low-Vision Featurexe2x80x94The large numeral on the back of the $10 note is easy to read. Also, a machine-readable feature has been incorporated for the blind. It will facilitate development of convenient scanning devices that could identify the note as a $10.
8. Fine Line Printing Patternsxe2x80x94The fine lines printed behind both the portrait and the U.S. Treasury Building are difficult to replicate.
9. Microprintingxe2x80x94Because they""re so small, microprinted words are hard to replicate. On the front of the note, xe2x80x9cTENxe2x80x9d is continually repeated in the numeral in the lower left-hand corner, and xe2x80x9cThe United States of Americaxe2x80x9d is repeated just above Hamilton""s name.
There are means such as light tables, ultraviolet lamps, and illuminated magnifiers to individually or in some cases in combination to examine these features, but none provide an ability in a compact low cost device to examine a sufficient number to be certain of a bills validity.
U.S. Pat. No. 5,444,263, Instrument For The Visual Recognition Of Authenticity Features In Banknotes And Security Documents, invented by Wolfgang R. Mastnak, hereinafter referred to as the Mastnak patent, teaches some of the concepts of the present invention but defines the optics as a cylindrical lens which is incapable of multidirectional magnification of the image. As such the Mastnak invention cannot adequately magnify the microprinting for recognition as it is unidirectional in its magnification. Secondly the method of illumination is also flawed as both the back and front illumination are caused by end illumination the lens and the diffuser. There is no mention of a mirror, prism, or other optical means of direction other than scattered light toward the lens. Likewise, end illumination of the lens has equal if not a more severe flaw in that the fingerlike or cylindrical lens acts as a light pipe and directs the photons toward the lens end distal to the lamp. Only minor scattering of light illuminates the currency in both cases. Mastnak recognizes the flaw in the illumination intensity by tying to enhance the illumination through edge lighting of both the cylindrical lens and diffuser. Again, the efficacy in illuminating the currency in this manner without benefit of directive optics is likewise flawed. Mastnak""s substitution of an ultraviolet lamp for the broadband visual spectrum lamp is similarly but more so flawed. Ultraviolet excited fluorescence visibility is very difficult to view in room light without having a shroud to limit the effects of ambient light. It is doubtfil that enough ultraviolet light will reach the phosphors in the thread to adequately fluoresce the thread with this optical arrangement.
The present invention resolves these limitations by providing a device with directed light sources to properly illuminate the currency, an omni-directional lens to magnify the microprinting and fine features for cognitive viewing and other novel features to enhance utility for viewing watermarks and color shifting inks.
An object of the present invention is to provide a device to omni-directionally magnify the document of interest sufficiently to view the microprinting, and print quality. Another object is to provide a device that can back illuminate the bill for viewing the security thread and watermark and other imbedded features or those having partial aligned images on both the front and rear surfaces. Yet another object is to provide a front illuminating source that can be used to detect and validate the color shifting ink. A further object is to provide ultraviolet illumination to excite the phosphorescence of the security thread. An additional object is to provide a light shield to reduce the amount of room light interference at the lens and improve the brightness and contrast of the image.
The present invention provides a means for positioning a document at a distance from a magnifying lens to create a magnified in focus image while providing a light source within the visible light spectrum to rear illuminate the paper currency. It has a magnifying lens that is useful for enlarging the microprinting located at various locations such as around the face and within the denominational numeral on US paper currency. The microprinting can be seen with either front or rear illumination on the front surface of the currency, while rear illumination is needed to view the polyester thread and the watermark in US currency and alignment features within some non US denominations. The thread has printing which can be seen more easily when magnified, especially the denomination printed in the star field.
Additional features may be added to the basic invention such as an ultraviolet light source in the uvA range to facilitate determination of the fluorescent color of the polyester thread. A lamp emitting at approximately 370 nm is useful for this purpose and is easily filtered to prevent eye damage. UvB and uvc will accomplish fluorescence but are also more harmful and not suggested for this application. In US currency, the thread in the 5-dollar bill glows blue, in the 10-dollar bill it glows orange, in the 20-dollar bill it glows green, in the 50-dollar bill it glows yellow, while in the 100-dollar bill it glows red. Said ultraviolet lamp may be placed in front of or to the rear of the currency. It might additionally be useful to add an ultraviolet filter between the lens and the ultraviolet source to shield the user from ultraviolet light. Furthermore, a diffuser may be advantageously placed between the light source and the currency to make the illumination more uniform.
In a further embodiment of the present invention, a mirror is placed between the lens and the currency at an angle below the lower edge of the currency or above the upper edge of the currency. Said mirror is useful for reflecting light onto the front face of the currency to view the color changing ink. Said color changing ink appears black when rear illuminated and a reflective green when front illuminated. A further embodiment replaces the mirror with a second light source to illuminate the front surface of the currency.
When viewing the watermark it may be useful to move the magnifying lens out of the way to view the watermark unmagnified.
Other objects of the present invention will become apparent to those skilled in the art in light of the following drawings and detailed description of the invention.